Must be true. As shown below, we can combine the statements that some manuscripts whose authenticity is suspect will be restored and that only frequently consulted manuscripts will be restored.

Could be false. The stimulus tells us that most manuscripts widely acknowledged to be of cultural significance will be restored. This allows us to infer that most of these manuscripts can have their safety ensured. But we don't know about all manuscripts widely acknowledged to be of cultural significance.

Could be false. As shown on our diagram, there are no necessary conditions attached to the condition of a manuscript’s safety being ensured. It is possible that some manuscripts exist whose safety can be ensured but are not frequently consulted. Although we know that there must be some manuscripts whose safety can be ensured that are frequently consulted by researchers, we don't know about all.

Could be false. The stimulus does not give us any information regarding what manuscripts are most susceptible to deterioration.

Could be false. Although we know that if a manuscript is rarely consulted, it won't be restored, it's still possible that a manuscript that is not restored is still of widely acknowledged cultural significance.